According to U.S. 2004/0083997A1 (JP-A-2004-150332), a conventional valve lift control device axially moves a control shaft to change a valve lift in accordance with the axial position of the control shaft. In this structure, a rotation cam and a contact member, which are in contact with each other, are used as an actuator that axially moves the control shaft. Torque is transmitted to a rotation cam, so that the rotation cam is driven. The contact member, which is a direct acting follower, links with the control shaft.
In this structure, the contact member is in contact with the rotation cam. Accordingly, when reactive force applied from a valve onto the control shaft becomes excessively small, and when the rotation cam rotates to the side, in which a cam lift decreases, the contact member may depart from the rotation cam. When the contact member departs from the rotation cam, the valve lift cannot be controlled, and an engine performance becomes unstable.